At present, as known, there are several types of independently operating and portable radiators such as radiators wherein circulating diathermal oil is heated by an electric resistance arranged inside the radiator casing.
These diathermal oil radiators usually have a number of radiating members mutually hydraulically connected by means of upper and lower hubs.
Each radiating member is constituted by a first and a second metal plate mutually associated in order to define a central portion wherein the diathermal oil circulates. In each radiating member, the surface portion extending outside the central portion where the oil circulates may have folds and/or channels and/or apertures on the double sheet metal defined by the mutual connection of the first and second plates. Those folds and/or channels and/or apertures tend to reduce the heat transmission from the central portion to the periphery of each radiating member.
In this manner the peripheral surfaces of the radiator are at a lower temperature than that of the heated oil circulating in the central portion. In spite of its good operation, this type of radiator has the inconvenience of being slow and of producing a perceptible convective motion when it is turned on and consequently of being slow at radiating heat to the surroundings. It usually takes in fact at least 7 to 8 minutes to create a convective motion because first the electrical resistance must heat up and then the diathermal oil and the radiating member array. Furthermore, these oil radiators have a relatively high manufacturing cost and accordingly a high retail price.
In fact, the provision of a grid above the radiator casing requires added work of stamping, stocking, degreasing, painting and assembling of the grid thereby increasing costs due to the materials and to the added production steps.